Circuit breaker with contact biasing means



March 1965 R. c. STROTHER ETAL 3,174,024

CIRCUIT BREAKER WITH CONTACT BIASING MEANS 5 Sheets-Sheet 1 Filed May 19, 1961 Fig. I

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WITNESSES INVENTORS Russell C. Sfrother 8 Jgh ATTORNEY March 1965 R. c. STROTHER ETAL 3,174,024

CIRCUIT BREAKER WITH CONTACT BIASING MEANS 3 SheetsSheet 2 Filed May 19. 1961 E 2. n2 5. r mm Z x 3 5 .0. km :1 I- a I no. pm. 3 L, mm H N: 1 mm mw a B m H &. um 5 x s a m: E u B mm. m z .l o! a m um, m m9 I WV mw w a 2. a. mpfi a M III mm E0 March 16, 1965 c, s o ETAL 3,174,024

CIRCUIT BREAKER WITH CONTACT BIASING MEANS 3 Sheets-Sheet 5 Filed May 19, 1961 77 em" as n United States Patent 3,174,024 CIRCUIT BREAKER WITH CQ NTACT BIASING MEANS Russell C. Strother, Rochester Borough, and John Zipay,

Daugherty Township, Beaver County, Pa, assiguors to Westinghouse Electric (Iorporation, Pittsburgh, Pa, a

corporation oi Pennsylvania Filed May 19, 1961, Ser. No. 111,313 Claims. ($1. 200-470) This invention relates to circuit breakers and more particularly to circuit breakers of the type having resilient means for maintaining contact pressure when the contacts of the circuit breaker are in the closed position.

In the patent to Julius Toth et al., Patent No. 2,654,008, there is shown and described a movable contact structure comprising an elongated contact arm that is pivotally connected, intermediate its ends, to a toggle mechanism. A movable contact is carried at one end of the movable contact arm and engages a fixed contact in the breaker structure. When the contacts are in the closed position, the contact arm is biased about its intermediate pivot, to maintain contact pressure, by means of a compression spring that is disposed between the base of the housing and the outer or non-contact-carrying end of the contact arm. When the contact arm is moved to the open position, the non-contact-carrying end thereof engages a stationary pin whereupon the contact arm pivots about this stationary pin to the open position.

For certain types of circuit breakers it is desirable to support the circuit interrupting mechanism between side plates as an independent operable unit. One advantage of this type of structure is that the circuit breaker mechanism can be assembled, tested and calibrated before it is mounted in the insulating housing. Other advantages of this type of structure will be hereinafter specifically described.

Since the contact arm described in the above-mentioned patent is supported by a compression spring that biases against the base of the housing, the operating mechanism of that structure cannot be assembled as a unit that is operable outside of the insulating housing.

Thus, an object of this invention is to provide a circuit breaker having a movable contact arm that operates with the desirable motion and results shown and described in the above-mentioned patent which circuit breaker comprises an operating mechanism that can be assembled as an operable unit outside of the insulating housing.

Another object of the invention is to provide a circuit breaker having an improved movable contact structure.

A more general object of the invention is to provide an improved circuit breaker that is relatively easy to assemble and inexpensive to manufacture.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

According to one embodiment of the invention, there is provided a circuit breaker comprising an insulating housing and a circuit-breaker mechanism disposed within the housing. The circuit-breaker mechanism is a unitary operating structure that comprises two insulating side plates having supported therebetween circuit interrupting means comprising an operating mechanism, a tripping mechanism, a contact structure and an arc-extinguishing structure. The contact structure includes two movable contacts each of which is supported on one end of an elongated movable contact carrying arm. The movable contact arms are pivotally connected intermediate their ends to the operating mechanism. When the contacts are in the closed position, the movable contact arms are biased about their intermediate pivot to maintain contact pre sure by means of a tension spring that is connected at 3,174,924 Patented Mar. 16, 1965 ice one end to a pin that is attached to the non-contact-carrying ends of the movable contact arms and at the other end to a stationary pin that is supported between the insulating side plates. The stationary pin is disposed in slots in the movable contact carrying arms so that the movable contact carrying arms can move with respect to the stationary pin when the contact arms are in the closed position. The tension spring biases the movable contact carrying arms about their intermediate pivot to thereby maintain contact pressure when the contact arms are in the closed position. During an opening operation, the contact arms move to first engage the stationary pin after which engagement they pivot about the stationary pin to the open position.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawings, in which:

FEGURE l is an elevational view of a circuit breaker embodying principles of the invention;

FIG. 2 is an elevational view, with one of the insulating side plates removed, of the circuit-breaker mechanism;

PEG. 3 is a top view of the mechanism shown in FIG. 2; both of the side plates being shown; but the operating handle and its associated parts being removed for the purpose of clarity;

PEG. 4 is a perspective view, partly in section, of the movable contact structure seen in FIGS. 2 and 3;

FIG. 5 is an elevational view of one of the insulating side plates shown in FIGS. 2 and 3;

FIGS. 6, 7 and 8 are eievational, end, and top views, respectively, of one of the supporting clips seen in FIG. 3;

FIGS. 9 and 10 are elevational and end views. respectively, of the main latch member shown in FIG. 2;

FIGS. 11 and 12 are elevational and end views, respectively, of the trip member shown in FIG. 2;

FIGS. 13 and 14- are elevational front and side views respectively of the armature member shown in FIG. 2; and,

FIG. 15 is a top view of one of the plates of the arcextinguishing structure shown in FIGS. 2 and 3.

Certain features of the circuit breaker of this invention are described and claimed in the copending application of Hiller D. Dorfman et al., Serial No. 112,172, filed May 19, 1961 and assigned to the assignee of the instant application.

Referring to the drawings, a circuit breaker 3 is shown in F168. 1 and 2 comprising a housing 5 of molded insulating material, and a unitary circuit-breaker mechanism 7 supported within the housing. The housing 5 comprises two halves, only one of which is shown in FIG. 1, that are secured together by means of four tubular rivets 12.

The unitary circuit-breaker mechanism 7, FIGS. 2 and 3, comprises a contact structure 13, an arc-extingushing structure 315, an operating mechanism 17 and a tripping mechanism 19. The circuit-breaker mechanism is supported between two insulating side plates 21, one of which side plates 21 is shown in detail in FIG. 5.

The contact st rcture 13 comprises a stationary contact 23 and two movable contacts 25, only one of the movable contacts 25 being shown in FIGS. 2 and 4. Each of the movable contacts 25 is supported on one end of a movable contact arm 27 (FIGS. 2, 3 and 4). One end of a tension spring 29 is supported at the non-contact-carrying ends of the two movable contact arms 27 on a pin 31 that is connected to the two movable contact arms 27. The other end of the spring 29 is attached to a pin 33 that is supported in openings 35 (FIG. 5) in the two insulating side plates 21. The pin 33 is positioned in slots 36 in the movable contact arms 27 so that the movable contact arms 27 can move relative to the pin 33 ar /aces when the contact arms are in the closed position. The spring 29 biases the contact arms 27 about a pivot pin 37 to provide contact pressure when the contacts 23, 25 are in the closed position.

The operating mechanism 17 includes a toggle, comprising a lower toggle link 38 that is pivotally connected to the movable contact arms 27 intermediate the ends of the contact arms 27 by means of the pivot pin 37. An upper toggle link 39 is connected at one end to the upper end of the lower toggle link 38 by means of a knee pivot pin 41. The upper end of the upper toggle link 39 is pivotally connected to a releasable latch member 4-3 by means of a pivot pin 45. The releasable member 43 is pivotally supported between the insulating side plates 21 by means of a pivot pin 47 that is supported in openings 49 (KG. in the side plates 21.

An operating member 51, having an inverted U-shaped construction is pivotally supported on the insulating side plates 21 in grooves 53 (FIG. 5). The legs of the U-shaped member 51 are prevented from moving 011 of the top surface of the insulating side plates 21 by means of clips 55 (FIGS. 68), each of which clips is held in place by the pin 33 (FIG. 3). The pin 33 extends through an opening 59 (1 1G. 6) in each of the clips 55 and is riveted over at its ends. Each of the clips 55 has an opening 61 (FIG. 8) therein for receiving one of the legs of the U-shaped member 51.

An operating handle 63 of molded insulating material is supported at the outer end of the U-shaped member 51. An arcuate portion 65 of the operating handle 63 substantially closes an opening in the molded housing 5 (FIG. 1), through which the operating handle 63 extends. Four springs 67 (only two of which are shown in FIG. 2) are connected at one end to two plates 61% (only one being shown in FIG. 2) that are connected to the knee pivot 41 of the toggle 38, 39. The springs 67 are connected at their other ends to an inverted U-shaped plate 69 that is supported at the outer end of the U-shaped member 51.

The contacts 23, are manually opened by movement of the operating handle 63 in a counterclockwise (FIG. 3) direction to the off position. This movement carries the line of the action of the overcenter springs 67 to the left of the pivot 41 causing collapse of the toggle 38, 39. As the toggle 38, 39 collapses the switch arms 27 first move to engage the pin 33 and thereafter the switch arms 27 rotate counterclockwise about the pin 33 to open the contacts 23, 25 with a snap action. Opening movement of the contact arms 27 is limited by engagement of the contact arms with a pin 70 (FIGS. 2 and 3) which pin 70 is supported in openings 71 (FIG. 5) in the side plates 21. Reverse or clockwise movement of the operating handle 63 (FIG. 2) to the on position moves the knee pivot 41 of the toggle 38, 39 to the right (FIG. 3) resetting the toggle .38, 39 and moving the contact arms 27 back to the closed position, shown in FIG. 3, with a snap action.

The trip structure 19 comprises a trip member 73 that is seen in detail in FIGS. ll and 12. The trip member 73 comprises a generally cylindrical trip bar 75 having a notch 77 therein, and a trip arm 79 having a flag portion 81 at the top thereof. The trip bar 75 is rotatably supported in openings 33 (PEG. 5) in the side plates 21.

A main latch 87 which is seen in detail in FIGS. 9 and 10, comprises a pin 88 that is rotatably supported in openings 89 (FIG. 5) in the side plates 21. The main latch 87 has a latch portion 91 that engages a latch portion 93 (FIG. 2) on the releasable member 43 to hold the releasable member in the latched position. The main latch 87 has a portion 95 that engages the periphery of the trip bar ipit gpposite the notch 77 (FIG. 12) when the parts at? in the latched position (PEG. 2). The trip member 73 is biased in a counterclockwise direction (FIG. 2) by means of a torsion spring 97. The main latch 87 A is biased in a counterclockwise direction by means of a torsion spring 99.

An armature member 1111 (seen in detail in FIGS. 13 and 14) comprises a pin 103 and a member 105 that has an armature 11W disposed at one end thereof and a projection 169 at the other end. The pin 193 of the armature member 1111 is rotatably supported in openings 111 (FIG. 5) in the insulating side plates 21. The armature member 1411 is biased in a counterclockwise direction (FIG. 3) by means of a torsion spring 112.

A bimetallic member 115 is attached at one end to a conductor 117. The free end of the bimetal 115 has a projection 119 thereon having a topped opening through which an adjusting or calibrating screw 121 extends. A U-shaped magnetic yoke 123 is attached to the conductor 117 opposite the armature 137.

The circuit though the circuit breaker mechanism (FIG. 3) extends from a conductor 127 that is attached at one end to the upper end of the conductor 117, through the conductor 117, flexible conductors 129 that are attached at one end .to the conductor 117 and at the other end to the contact arms 27, the contact arms 27, the contacts 23, 25 and a conductor 131.

Solderless terminal connectors 132 (FIG. 1) of a type well known in the art, are attached to the outer ends of the conductors 127 and 131 and are provided to enable connection of the circuit breaker 3 in an electrical circuit in a manner well known in the art.

The conductor 117 has three project-ions 133 (FIG. 2) at each side thereof which projections fit in openings 134 (FIG. 5) in the side plates 21 to support the conductor 117, and the parts that are connected thereto, on the side plates 21. The conductor 131 has two projections 135 and 136 (FIG. 2) at each side thereof which projections lit in openings 137 and 138 (-FIG. 5), respectively, in the side plates 21 to support the conductor 131, and the parts that are connected to the conductor 131, on the side plates 21.

Two openings 139 (FIG. 5) are provided in each of the side plates 21. When the circuit-breaker mechanism 7 (FIGS. 2 and 3) is mounted in the insulating housing 5 (FIG. 1), two projections (not shown) that are molded integral with each of the halves of the insulating housing 5, fit within the openings 139 in the side plates 21 to position and support the circuit-breaker mechanism 7 within the housing.

When an overload current below a predetermined value passes through the circuit breaker, the bimetallic member 115 is heated and it bends to the right (FIG. 2) whereupon the calibrating screw 121 engages the flag portion 81 of the trip member 73 rotating the trip member 73 in a clockwise direction about the pivot 75. During this movement the portion 95 of the main latch 87 rides off of the periphery of the trip bar 75 and snaps clockwise into the notch 77 (FIG. 12) of the trip bar 75. During this clockwise movement of the main latch 87, the latch portion 91 thereon rotates free of the latch portion 93 of the releasable member 43 to release the member 43. When released, the member 43 rotates clockwise about its pivot 47 under the bias of the springs 67, causing collapse of the toggle 38, 39, and opening of the switch arms 27 about the pivot 33. During this movement, the handle 63 is moved, in a manner well known in the art, to a tripped position intermediate the on and off positions, thereby giving a visual indication that a tripping operation has occurred.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accomplished by moving the handle 63 in a counterclockwise direction from the intermediate or tripped position to the extreme off position. During this movement, a projection 140 on the U-shaped member 51 engages a shoulder 141 on the releasable member 43 moving the releasable member 43 counterclockwise about its pivot 47. Near the end of this movement, the lower rounded part of the latch portion $3 of the releasable member 43 engages an outwardly extending arm 142 on the main latch 87 and moves the main latch to the latching position. As soon as the portion 95 of the main latch 87 clears the edge adjacent the notch 77 (FIG. 12) of the trip bar 7'5, the torsion spring 57 (FIG. 2) rotates the trip member 73 clockwise to the latched position. The latch portion 91 of the main latch 8'7 is then in position engaging the latch portion 93 of the releasable member 43 so that upon release of the handle 63, the mechanism is latched and the contacts can be closed in the previously describd manner by movement of the handle as to the on position.

Upon the occurrence of an overload current above the predetermined value, the magnetic yoke 12?) is energized sufiiciently to attract the armature m7 to rotate the armature 161 clockwise about its pivot 1G3, whereupon the upper projetcion 109 on .the armature member ltll engages the flange portion fill of the trip member 73 rotating the trip member 73 clockwise to eiiect release of the main latch 87 and release of the releasable member 43 to thereby eiiect a tripping operation in the same manner hereinbefore described.

When the contacts 23, 25 open, an arc is established between each of the movable contacts 25 and the stationary contact 23. These arcs are extinguished by means of the arc-extinguishing structure 15. The arc-extinguishing structure comprises the two insulating side plates 21, a plurality of arc-extinguishing members or plates 151 (one of which is shown in detail in FIG. 15), an arc-runner plate 152 that is connected to the stationary contact 23, a plate 153 backing up the arc runner plate 152, two insulating plates 154 and an insulating plate 155. Each of the arc-extinguishing plates 151 has two notches 159 (FIG. 15) therein. Each of the arc-extinguishing plates 151 is supported between the insulating side plates 21 by means of elongated projections lei (FIG. 15) that fit in the openings 63 (PEG. 5) in the side plates Zll. Projections 162 on each side of the arcrunner plate 15?; and on each side of the arc-runner supporting plate 153 fit in the openings 138 (FIG. 5) in the insulating side plates 21 to support the plates 152 and 153 on the side plates Zl.

The arc-extinguishing plates 151 of the arc-extinguishing structure 15 can be of insulating material to elongate the arcs for extinction. Preferably, however, the plates are of a magnetic and conducting material such as steel to draw the arcs into the plates where they are broken up into a plurality of short serially related arcs that are extinguished in a manner Well known in the art. A detailed description of the theory of arc-interruption is set forth in the patent to l. A. Kalaway, Patent No. 2,590; 543, issued March 25, 1952 and assigned to the assignee of the instant application.

During the opening operation, when the contact arms 27 move away from the contact 23, the two arcs established between the two contacts and the contact 23, are magnetically attracted along the arc-runner plate 152 and into the slots 159 (FIG. 15) of the magnetic plates 151 to be broken up into a plurality of serially related arc portions, which are portions are rapidly extinguished in a manner well known in the art.

The insulating plates 154 and 155 have projections 171 thereon that engage in openings 137 and 173 (FIG. 5) in the insulating side plates 21 to support the plates 154 and 155 on the side plates 21. These insulating members 153, 155 are provided to block the gases, that are generated upon extinction of the arc, from moving back into the operating portion of the circuit breaker.

With the improved contact structure, an improved circuit breaker is provided that includes a unitary circuitbreaker mechanism. Advantages of making the circuitbreaker mechanism as a unitary structure are as follows: The mechanism can be tested and calibrated prior to its being mountedwithin the insulating housing; Assembly is easier since there is convenient access to the pants. The calibration is automatically sealed when the mechanism is mounted in the housing. If the molded housing is broken during or after assembly, the mechanism can be salvaged as a unit that is calibrated and ready to be mounted in another housing. Since the mechanism functions as a unitary operating structure, shrinkage or warpage of the molded insulating housing will have little effect on. the calibration of the circuit breaker.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising, in combination, a housing, a circuit-breaker mechanism supported within said housing, said circuit-breaker mechanism comprising a unitary structure comprising spaced side plates and circuit interrupting means supported by said spaced side plates, said circuit interrupting means comprising an operating mechanism, a stationary contact, a movable contact cooperable with said stationary contact to open and close a circuit, an elongated movable contact arm carrying said movable contact at one end thereof, means pivotally connecting said movable contact arm intermediate the ends thereof to said operating mechanism, and tension spring means connected to said movable contact arm at the noncontact-carrying end of said movable contact arm to bias said movable contact arm about said intermediate pivot to maintain pressure between said contacts when said contacts are in the closed position.

2. A circuit breaker comprising, in combination, an insulating housing, a circuit-breaker mechanism supported within said housing, said circuit-breaker mechanism comprising spaced side plates and circuit interrupting means supported on said side plates, said circuit interrupting means comprising a stationary contact, a movable contact cooperable with said stationary contact to open and close a circuit, an elongated movable contact arm carrying said movable contact at one end thereof, an operating mech anism pivotally connected to said movable contact arm intermediate the ends of said movable contact arm, a first spring support stationarily supported on said side plates near the non-contact-carrying end of said movable contact arm, a second spring support carried by said noncontact-carrying end of said movable contact arm, a. spring supported under tension at one end on said first spring support and at the other end on said second spring support, and said spring biasing said movable contract arm about said intermediate pivot to exert a closing force on said movable contact arm when said movable contact arm is in the closed position.

3. A circuit breaker comprising, in combination, an insulating housing. a circuit-breaker mechanism supported within said housing, said circuit-breaker mechanism comprising a unitary structure comprising spaced side plates and circuit interrupting means supported by said side plates, said circuit interrupting means comprising a stationary contact, a movable contact cooperable with said stationary contact to open and close a circuit, an elongated movable contact arm carrying said movable contact at one end thereof, an operating mechanism comprising a toggle pivotally connected to said movable contact arm intermediate the ends of said movable contact arm, a first spring support station-arily supported by said spaced side plates, :1 second spring suppont carried by said movable contact arm near the non-contact-carrying end of said movable contact arm, a spring supported at one end on said first spring support and at the other end on said second spring support, said movable contact arm in the closed position being movable relative to said first spring support, said spring biasing said movable contact arm about said intermediate pivot to exert a closing force on said movable contact arm When said movable contact arm is in the closed position, means for operating said operating mechanism to open and close said contacts, and said movable contact arm engaging said first spring support and pivoting about said first spring support during an opening operation.

4. A circuit breaker comprising, in combination, a stationary contact, a movable contact cooperable with said stationary contact to open and close a circuit, an elongated movable contact arm carrying said movable contact at one end thereof, an operating mechanism pivotally connected to said movable contact arm intermediate the ends of said movable contact arm, a first spring support stationarily supported in proximity to the non-contact-carrying end of said movable contact arm, a second spring support carried by said movable contact arm, a spring sup ported under tension at one end on said first spring support and at the other end on said second spring support, said spring biasing said movable contact arm about said interrupting means supported on said spaced side plates,

said circuit interrupting means comprising a stationary contact, a movable contact cooperable with said stationary contact to open and close a circuit, an elongated movable contact arm carrying said movable contact at one end thereof, an operating mechanism comprising a toggle pivotally conn cted to said movable contact arm intermediate the ends of said movable contact arm, a first spring support stationarily supported on said spaced side plates near the non-contact-carrying end of said movable contact arm, a second spring support carried by said movable contact arm, a spring supported under tension at one end on said first spring support and at the other end on said second spring support, said movable contact arm being movable relative to said first spring support when said contacts are in the closed position, said spring biasing said movable contact arm about said intermediate pivot to exert a closing force on said movable contact arm When said movable contact arm is in the closed position, means for operating said operating mechanism to open and close said contacts, and said movable contact arm engaging said first spring support and pivoting about said first spring support during an opening operation.

Reierences Qited by the Examiner UNITED STATES PATENTS 2,419,125 4/47 Dorfman et al. 200-170 2,531,350 11/50 Chrastina 200-168 2,652,465 9/53 Jackson 200-116 2,654,008 9/53 Toth et al. 20088 2,734,115 2/56 Dupre 200l68 2,889,437 6/59 Christensen 200--168 2,925,481 2/60 Casey 200-116 BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, Examiner. 

1. A CIRCUIT BREAKER COMPRISING, IN COMBINATION, A HOUSING, A CIRCUIT-BREAKER MECHANISM SUPPORTED WITHIN SAID HOUSING, SAID CIRCUIT-BREAKER MECHANISM COMPRISING A UNITARY STRUCTURE COMPRISING SPACED SIDE PLATES AND CIRCUIT INTERRUPTING MEANS SUPPORTED BY SAID SPACED SIDE PLATES, SAID CIRCUIT INTERRUPTING MEANS COMPRISING AN OPERATING MECHANISM, A STATIONARY CONTACT, A MOVABLE CONTACT COOPERABLE WITH SAID STATIONARY CONTACT TO OPEN AND CLOSE A CIRCUIT, AN ELONGATED MOVABLE CONTACT ARM CARRYING SAID MOVABLE CONTACT AT ONE END THEREOF, MEANS PIVOTALLY CONNECTING SAID MOVABLE CONTACT ARM INTERMEDIATE THE ENDS THEREOF TO SAID OPERATING MECHANISM, AND TENSION SPRING MEANS CONNECTED TO SAID MOVABLE CONTACT ARM AT THE NONCONTACT-CARRYING END OF SAID MOVABLE CONTACT ARM TO BIAS SAID MOVABLE CONTACT ARM ABOUT SAID INTERMEDIATE PIVOT TO MAINTAIN PRESSURE BETWEEN SAID CONTACTS WHEN SAID CONTACTS ARE IN THE CLOSED POSITION. 